twitter/commons — pull request #342 by jsirois (2014-12-19 23:47:18+00:00)
Title: Use Travis CIs new container based builds.

The announcement is here:
http://blog.travis-ci.com/2014-12-17-faster-builds-with-container-based-infrastructure
The specs here:
http://docs.travis-ci.com/user/workers/container-based-infrastructure
http://docs.travis-ci.com/user/caching/#Fetching-and-storing-caches

This also turns on caching for ~/.pants.d, ~/.ivy2
and the current pants version bootstraped in
build-support. To make virtualenv caching work, updates
the virtualenv bootstrap script to use a stable directory name
across virtualenv versions.